jack-sys: search for jack library with pkg-config (#154)

* jack-sys: search for jack library with pkg-config

This fixes linking with PipeWire's JACK headers.
Fixes #142

* jack-sys: add package.links=jack to Cargo.toml

jack-sys/Cargo.toml

@@ -6,8 +6,12 @@ authors = ["Patrick Reisert"]
 description = "Low-level binding to the JACK audio API."
 repository = "https:/RustAudio/rust-jack/tree/main/jack-sys"
 license = "MIT OR Apache-2.0"
+links = "jack"
 
 [dependencies]
 libc = "0.2"
 libloading = "0.6"
 lazy_static = "1.4"
+
+[build-dependencies]
+pkg-config = "0.3"

jack-sys/build.rs

@@ -0,0 +1,7 @@
+fn main() {
+ // pkg-config is required to find PipeWire's implementation of libjack
+ // Refer to https:/RustAudio/rust-jack/issues/142 for details.
+ // Do not unwrap this because linking might still work if pkg-config is
+ // not installed, for example on Windows.
+ let _ = pkg_config::probe_library("jack");
+}